The NTP Biomolecular Screening Branch (BSB) develops and carries out programs in medium and high throughput screening (HTS) of environmental substances for rapid detection of biological activities of significance to toxicology. The BSB specifically administers the NTP HTS program initiative to implement its vision for toxicology in the 21st century; this vision places an increased emphasis on the use of alternative assays for targeting the key pathways, molecular events, or processes linked to disease or injury, and attempts to incorporate them into a research and testing framework.